Front hanger for convertible tandem bicycles



' Oct. 2, 1945. D. A. SWANSON FRONT HANGER FOR CONVERTIBLE TANDEM BICYCLES Filed Ma 5 1943} M w w m Y NmR. aw cs/wa i mw g Patented Oct. 2, 1945 This inventionrelates t impmvement n a drivefor convertible tandem bicycles; and it conent n .3 91.

sists in the constructions, arrang binatlons"herein-described and 1 clai ix 'ed; L I

More particularly; the, drive "concerns that" type in which a rear-crank shaft is mounted within or extended through the rear wheel hub and interconnected with a usual front sprocket to effect propulsion of a bicycle.

It is the cardinal object of the invention to provide a connection between the front sprockets which will permit the quick conversion of the bicycle from single to tandem use at the will-of the driver, and without the use of tools.

It is also an object of the invention to provide a connecting means for the front sprockets along lines of simplicity and durability, so as to reduce the cost of manufacture.

It is a still further and important object of the invention to provide a connecting means for the front sprockets without the need for threading or any other keying or securing devices other than that ordinarily employed in hanger constructions of the type specified.

Additional objects, advantages and features of invention will be apparent from the following description considered in conjunction with the accompanying drawing, wherein Figure 1 is a fragmentary side elevation of a convertible tandem bicycle having my mechanism installed.

Figure 2 is an enlarged fragmentary side elevation illustrating the front driving sprockets in disengaged position.

Figure 3 is a vertical cross section through the structure shown in Figure 2.

Figure 4 is a similar view illustrating the sprockets in connected relation for tandem use.

Figure 5 is a cross section on the line 5-5 of Figure 4.

Figure 6 is an elevational view illustrating the relation of the hub of the driving sprocket and idling sprocket in disengaged position.

Reference is first made to Figure 1 of the drawing, wherein there is illustrated the rear portion of a tandem bicycle ID, the rear wheel of which is indicated at I I. The rear wheel includes sprockets l3 and I4 and a crank shaft I2 upon which there is mounted pedal cranks I5. This construction may be similar to that shown in my Patent No. 2,277,727. The front crank hanger l6 revolubly mounts a crank shaft I1 adjacent to one end of which there is keyed or otherwise fixed a sprocket IS. The sprocket I8 is provided with a hub l9 through which the crank shaft is extended and were key JThe'hub hasf integrally formed therewith a'sleeve' '2 0 for mounting of a normally" free run ning sprocket 2| aswill bedescribed. ;"I he hub I9 .i s also formed withflats 22 adaptedtoalign with flats formed in the ,hub 23 of "the sprocket 2| and when in engaged position, the spinckets' l8 and 2| will be rotated in unison.

Within the hub 23 a ball bearing assembly 24 is housed, the inner race 25 of which is mounted on the hub 20 and is provided with a pair of recesses '26 longitudinally spaced upon the inner periphery thereof. A spring-pressed detent 21 is alternatively complemental to the recesses 26 for maintaining the sprocket 2| in operative or inoperative position with the driven hub I9 of the sprocket iii.

A dust or closure plate 28 is detachably mounted upon the sprocket 2| by means of machine screws 29 and 29', the plate being apertured to receive the sleeve 20 therethrough and lies snugly against the bearing assembly 24, thereby preventing ingress of foreign particles into the bearing assembly. The screw 29 is slightly longer than the screws 29 and mounts a sliding catch 30. In the present instance, the catch is shown as having an elongated slot 3| for receiving the screw 29. The catch 30 is slidable toward and away from the sleeve 20 so as to present its lower end behind a shoulder 32 of the crank pedal 33, when the sprockets l8 and 2! are in connected relation.

The sleeve 20 is here shown as having a tongue 34 at its end adapted to engage in a slot 35 of the pedal crank, the latter being keyed to the shaft H as at 36. By this construction a single key 36 functions to secure the pedal crank 33, the sleeve 20 and the gear [8 for unitary rotation, and it will be seen that by eliminating key devices for the gear l8, special machining has been avoided, as well as maintaining normal strength of the shaft.

In a convertible tandem as illustrated in Figure l, the power applied to the rear driving sprocket l4, through the rear pedal cranks l5 is'transmitted through a chain' 31 to the front driven sprocket 2|, which ordinarily idles freely upon the front crank shaft so that a single rider may rotate the front crank shaft without the added friction of a second chain, but which, when connected to the main driving sprocket I8 transmits the power through chain 38 to the rear wheel sprocket I3 in the usual manner.

We will assume that the sprockets i8 and 2| are in the positions shown in Figure 3, and it isdesired to convert the bicycle to a tandem drive which will require that the sprockets be connected for unitary rotation. In order that this may be done, it is only necessary to exert a lateral presallowing the "catch'l30I tos1ide downwardlybehind i; the shoulder 32 of the'pedal cran'kfi Thesprocket" 2| is thus rigidly connected to the shaft i1 and shoulder of the crank pedal and then secured by V tightening the screw 29'. The gear"-2l is '-next shifted laterally, so as to be free of the flats' fl. 7

While I have shown and described a prefer ed form of the device, this is by way of illustration only, and I consider. asmy; own, all such modi-.I

flcations'in construction asffairly fall within the scope ofthe appended claims; I v

m 2 V i 2,385,892 a ,Tif. LP??? fixed to the shaft and including a hub portion having flats on its periphery, a normally free '1; In'fa' tande drive r61 bicycles "or the like". 25 WWW? .i QM Q Viffih r l e 9 3;

ried by saidEidIing sprOQket movable o *a position betweenthehrarik' pedal and the idlihgsprocket I r, ior maintaining the latter in coupled engagement sprocket [8. To convert the bicycle to solo oper-' ation, the screw 29 is loosened, thecatch raised to; .1 5 an upper position so as to be removed from the -1 5 with the first named sprocket. '2 .;;.In atandem. drive for bicycles and the like including a front pedal drive shaft, a sprocket fixed to the shaft and including an integral axial sleeve; ah'o'rmally free idling sprocket on the sleeve shiitable laterally to engage the first named sprocket for interlocking engagement therewith. a. crank-pedal fixed to the outer end of the drive shaft and manually operable means on the idling 

